1 /*
2  * Copyright (C) 2008 The Android Open Source Project
3  *
4  * Licensed under the Apache License, Version 2.0 (the "License");
5  * you may not use this file except in compliance with the License.
6  * You may obtain a copy of the License at
7  *
8  *      http://www.apache.org/licenses/LICENSE-2.0
9  *
10  * Unless required by applicable law or agreed to in writing, software
11  * distributed under the License is distributed on an "AS IS" BASIS,
12  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
13  * See the License for the specific language governing permissions and
14  * limitations under the License.
15  */
16 #include <stdlib.h>
17 #include <string.h>
18 
19 #define LOG_TAG "NetlinkEvent"
20 #include <cutils/log.h>
21 
22 #include <sysutils/NetlinkEvent.h>
23 
24 #include <sys/types.h>
25 #include <sys/socket.h>
26 #include <netinet/in.h>
27 #include <netinet/icmp6.h>
28 #include <arpa/inet.h>
29 #include <net/if.h>
30 
31 #include <linux/if.h>
32 #include <linux/if_addr.h>
33 #include <linux/if_link.h>
34 #include <linux/netfilter/nfnetlink.h>
35 #include <linux/netfilter/nfnetlink_log.h>
36 #include <linux/netfilter_ipv4/ipt_ULOG.h>
37 
38 /* From kernel's net/netfilter/xt_quota2.c */
39 const int LOCAL_QLOG_NL_EVENT = 112;
40 const int LOCAL_NFLOG_PACKET = NFNL_SUBSYS_ULOG << 8 | NFULNL_MSG_PACKET;
41 
42 #include <linux/netlink.h>
43 #include <linux/rtnetlink.h>
44 
45 #include <netlink/attr.h>
46 #include <netlink/genl/genl.h>
47 #include <netlink/handlers.h>
48 #include <netlink/msg.h>
49 
NetlinkEvent()50 NetlinkEvent::NetlinkEvent() {
51     mAction = Action::kUnknown;
52     memset(mParams, 0, sizeof(mParams));
53     mPath = NULL;
54     mSubsystem = NULL;
55 }
56 
~NetlinkEvent()57 NetlinkEvent::~NetlinkEvent() {
58     int i;
59     if (mPath)
60         free(mPath);
61     if (mSubsystem)
62         free(mSubsystem);
63     for (i = 0; i < NL_PARAMS_MAX; i++) {
64         if (!mParams[i])
65             break;
66         free(mParams[i]);
67     }
68 }
69 
dump()70 void NetlinkEvent::dump() {
71     int i;
72 
73     for (i = 0; i < NL_PARAMS_MAX; i++) {
74         if (!mParams[i])
75             break;
76         SLOGD("NL param '%s'\n", mParams[i]);
77     }
78 }
79 
80 /*
81  * Returns the message name for a message in the NETLINK_ROUTE family, or NULL
82  * if parsing that message is not supported.
83  */
rtMessageName(int type)84 static const char *rtMessageName(int type) {
85 #define NL_EVENT_RTM_NAME(rtm) case rtm: return #rtm;
86     switch (type) {
87         NL_EVENT_RTM_NAME(RTM_NEWLINK);
88         NL_EVENT_RTM_NAME(RTM_DELLINK);
89         NL_EVENT_RTM_NAME(RTM_NEWADDR);
90         NL_EVENT_RTM_NAME(RTM_DELADDR);
91         NL_EVENT_RTM_NAME(RTM_NEWROUTE);
92         NL_EVENT_RTM_NAME(RTM_DELROUTE);
93         NL_EVENT_RTM_NAME(RTM_NEWNDUSEROPT);
94         NL_EVENT_RTM_NAME(LOCAL_QLOG_NL_EVENT);
95         NL_EVENT_RTM_NAME(LOCAL_NFLOG_PACKET);
96         default:
97             return NULL;
98     }
99 #undef NL_EVENT_RTM_NAME
100 }
101 
102 /*
103  * Checks that a binary NETLINK_ROUTE message is long enough for a payload of
104  * size bytes.
105  */
checkRtNetlinkLength(const struct nlmsghdr * nh,size_t size)106 static bool checkRtNetlinkLength(const struct nlmsghdr *nh, size_t size) {
107     if (nh->nlmsg_len < NLMSG_LENGTH(size)) {
108         SLOGE("Got a short %s message\n", rtMessageName(nh->nlmsg_type));
109         return false;
110     }
111     return true;
112 }
113 
114 /*
115  * Utility function to log errors.
116  */
maybeLogDuplicateAttribute(bool isDup,const char * attributeName,const char * messageName)117 static bool maybeLogDuplicateAttribute(bool isDup,
118                                        const char *attributeName,
119                                        const char *messageName) {
120     if (isDup) {
121         SLOGE("Multiple %s attributes in %s, ignoring\n", attributeName, messageName);
122         return true;
123     }
124     return false;
125 }
126 
127 /*
128  * Parse a RTM_NEWLINK message.
129  */
parseIfInfoMessage(const struct nlmsghdr * nh)130 bool NetlinkEvent::parseIfInfoMessage(const struct nlmsghdr *nh) {
131     struct ifinfomsg *ifi = (struct ifinfomsg *) NLMSG_DATA(nh);
132     if (!checkRtNetlinkLength(nh, sizeof(*ifi)))
133         return false;
134 
135     if ((ifi->ifi_flags & IFF_LOOPBACK) != 0) {
136         return false;
137     }
138 
139     int len = IFLA_PAYLOAD(nh);
140     struct rtattr *rta;
141     for (rta = IFLA_RTA(ifi); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
142         switch(rta->rta_type) {
143             case IFLA_IFNAME:
144                 asprintf(&mParams[0], "INTERFACE=%s", (char *) RTA_DATA(rta));
145                 mAction = (ifi->ifi_flags & IFF_LOWER_UP) ? Action::kLinkUp :
146                                                             Action::kLinkDown;
147                 mSubsystem = strdup("net");
148                 return true;
149         }
150     }
151 
152     return false;
153 }
154 
155 /*
156  * Parse a RTM_NEWADDR or RTM_DELADDR message.
157  */
parseIfAddrMessage(const struct nlmsghdr * nh)158 bool NetlinkEvent::parseIfAddrMessage(const struct nlmsghdr *nh) {
159     struct ifaddrmsg *ifaddr = (struct ifaddrmsg *) NLMSG_DATA(nh);
160     struct ifa_cacheinfo *cacheinfo = NULL;
161     char addrstr[INET6_ADDRSTRLEN] = "";
162     char ifname[IFNAMSIZ] = "";
163 
164     if (!checkRtNetlinkLength(nh, sizeof(*ifaddr)))
165         return false;
166 
167     // Sanity check.
168     int type = nh->nlmsg_type;
169     if (type != RTM_NEWADDR && type != RTM_DELADDR) {
170         SLOGE("parseIfAddrMessage on incorrect message type 0x%x\n", type);
171         return false;
172     }
173 
174     // For log messages.
175     const char *msgtype = rtMessageName(type);
176 
177     struct rtattr *rta;
178     int len = IFA_PAYLOAD(nh);
179     for (rta = IFA_RTA(ifaddr); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
180         if (rta->rta_type == IFA_ADDRESS) {
181             // Only look at the first address, because we only support notifying
182             // one change at a time.
183             if (maybeLogDuplicateAttribute(*addrstr != '\0', "IFA_ADDRESS", msgtype))
184                 continue;
185 
186             // Convert the IP address to a string.
187             if (ifaddr->ifa_family == AF_INET) {
188                 struct in_addr *addr4 = (struct in_addr *) RTA_DATA(rta);
189                 if (RTA_PAYLOAD(rta) < sizeof(*addr4)) {
190                     SLOGE("Short IPv4 address (%zu bytes) in %s",
191                           RTA_PAYLOAD(rta), msgtype);
192                     continue;
193                 }
194                 inet_ntop(AF_INET, addr4, addrstr, sizeof(addrstr));
195             } else if (ifaddr->ifa_family == AF_INET6) {
196                 struct in6_addr *addr6 = (struct in6_addr *) RTA_DATA(rta);
197                 if (RTA_PAYLOAD(rta) < sizeof(*addr6)) {
198                     SLOGE("Short IPv6 address (%zu bytes) in %s",
199                           RTA_PAYLOAD(rta), msgtype);
200                     continue;
201                 }
202                 inet_ntop(AF_INET6, addr6, addrstr, sizeof(addrstr));
203             } else {
204                 SLOGE("Unknown address family %d\n", ifaddr->ifa_family);
205                 continue;
206             }
207 
208             // Find the interface name.
209             if (!if_indextoname(ifaddr->ifa_index, ifname)) {
210                 SLOGD("Unknown ifindex %d in %s", ifaddr->ifa_index, msgtype);
211             }
212 
213         } else if (rta->rta_type == IFA_CACHEINFO) {
214             // Address lifetime information.
215             if (maybeLogDuplicateAttribute(cacheinfo, "IFA_CACHEINFO", msgtype))
216                 continue;
217 
218             if (RTA_PAYLOAD(rta) < sizeof(*cacheinfo)) {
219                 SLOGE("Short IFA_CACHEINFO (%zu vs. %zu bytes) in %s",
220                       RTA_PAYLOAD(rta), sizeof(cacheinfo), msgtype);
221                 continue;
222             }
223 
224             cacheinfo = (struct ifa_cacheinfo *) RTA_DATA(rta);
225         }
226     }
227 
228     if (addrstr[0] == '\0') {
229         SLOGE("No IFA_ADDRESS in %s\n", msgtype);
230         return false;
231     }
232 
233     // Fill in netlink event information.
234     mAction = (type == RTM_NEWADDR) ? Action::kAddressUpdated :
235                                       Action::kAddressRemoved;
236     mSubsystem = strdup("net");
237     asprintf(&mParams[0], "ADDRESS=%s/%d", addrstr, ifaddr->ifa_prefixlen);
238     asprintf(&mParams[1], "INTERFACE=%s", ifname);
239     asprintf(&mParams[2], "FLAGS=%u", ifaddr->ifa_flags);
240     asprintf(&mParams[3], "SCOPE=%u", ifaddr->ifa_scope);
241 
242     if (cacheinfo) {
243         asprintf(&mParams[4], "PREFERRED=%u", cacheinfo->ifa_prefered);
244         asprintf(&mParams[5], "VALID=%u", cacheinfo->ifa_valid);
245         asprintf(&mParams[6], "CSTAMP=%u", cacheinfo->cstamp);
246         asprintf(&mParams[7], "TSTAMP=%u", cacheinfo->tstamp);
247     }
248 
249     return true;
250 }
251 
252 /*
253  * Parse a QLOG_NL_EVENT message.
254  */
parseUlogPacketMessage(const struct nlmsghdr * nh)255 bool NetlinkEvent::parseUlogPacketMessage(const struct nlmsghdr *nh) {
256     const char *devname;
257     ulog_packet_msg_t *pm = (ulog_packet_msg_t *) NLMSG_DATA(nh);
258     if (!checkRtNetlinkLength(nh, sizeof(*pm)))
259         return false;
260 
261     devname = pm->indev_name[0] ? pm->indev_name : pm->outdev_name;
262     asprintf(&mParams[0], "ALERT_NAME=%s", pm->prefix);
263     asprintf(&mParams[1], "INTERFACE=%s", devname);
264     mSubsystem = strdup("qlog");
265     mAction = Action::kChange;
266     return true;
267 }
268 
269 /*
270  * Parse a LOCAL_NFLOG_PACKET message.
271  */
parseNfPacketMessage(struct nlmsghdr * nh)272 bool NetlinkEvent::parseNfPacketMessage(struct nlmsghdr *nh) {
273     int uid = -1;
274     int len = 0;
275     char* raw = NULL;
276 
277     struct nlattr *uid_attr = nlmsg_find_attr(nh, sizeof(struct genlmsghdr), NFULA_UID);
278     if (uid_attr) {
279         uid = ntohl(nla_get_u32(uid_attr));
280     }
281 
282     struct nlattr *payload = nlmsg_find_attr(nh, sizeof(struct genlmsghdr), NFULA_PAYLOAD);
283     if (payload) {
284         /* First 256 bytes is plenty */
285         len = nla_len(payload);
286         if (len > 256) len = 256;
287         raw = (char*) nla_data(payload);
288     }
289 
290     char* hex = (char*) calloc(1, 5 + (len * 2));
291     strcpy(hex, "HEX=");
292     for (int i = 0; i < len; i++) {
293         hex[4 + (i * 2)] = "0123456789abcdef"[(raw[i] >> 4) & 0xf];
294         hex[5 + (i * 2)] = "0123456789abcdef"[raw[i] & 0xf];
295     }
296 
297     asprintf(&mParams[0], "UID=%d", uid);
298     mParams[1] = hex;
299     mSubsystem = strdup("strict");
300     mAction = Action::kChange;
301     return true;
302 }
303 
304 /*
305  * Parse a RTM_NEWROUTE or RTM_DELROUTE message.
306  */
parseRtMessage(const struct nlmsghdr * nh)307 bool NetlinkEvent::parseRtMessage(const struct nlmsghdr *nh) {
308     uint8_t type = nh->nlmsg_type;
309     const char *msgname = rtMessageName(type);
310 
311     // Sanity check.
312     if (type != RTM_NEWROUTE && type != RTM_DELROUTE) {
313         SLOGE("%s: incorrect message type %d (%s)\n", __func__, type, msgname);
314         return false;
315     }
316 
317     struct rtmsg *rtm = (struct rtmsg *) NLMSG_DATA(nh);
318     if (!checkRtNetlinkLength(nh, sizeof(*rtm)))
319         return false;
320 
321     if (// Ignore static routes we've set up ourselves.
322         (rtm->rtm_protocol != RTPROT_KERNEL &&
323          rtm->rtm_protocol != RTPROT_RA) ||
324         // We're only interested in global unicast routes.
325         (rtm->rtm_scope != RT_SCOPE_UNIVERSE) ||
326         (rtm->rtm_type != RTN_UNICAST) ||
327         // We don't support source routing.
328         (rtm->rtm_src_len != 0) ||
329         // Cloned routes aren't real routes.
330         (rtm->rtm_flags & RTM_F_CLONED)) {
331         return false;
332     }
333 
334     int family = rtm->rtm_family;
335     int prefixLength = rtm->rtm_dst_len;
336 
337     // Currently we only support: destination, (one) next hop, ifindex.
338     char dst[INET6_ADDRSTRLEN] = "";
339     char gw[INET6_ADDRSTRLEN] = "";
340     char dev[IFNAMSIZ] = "";
341 
342     size_t len = RTM_PAYLOAD(nh);
343     struct rtattr *rta;
344     for (rta = RTM_RTA(rtm); RTA_OK(rta, len); rta = RTA_NEXT(rta, len)) {
345         switch (rta->rta_type) {
346             case RTA_DST:
347                 if (maybeLogDuplicateAttribute(*dst, "RTA_DST", msgname))
348                     continue;
349                 if (!inet_ntop(family, RTA_DATA(rta), dst, sizeof(dst)))
350                     return false;
351                 continue;
352             case RTA_GATEWAY:
353                 if (maybeLogDuplicateAttribute(*gw, "RTA_GATEWAY", msgname))
354                     continue;
355                 if (!inet_ntop(family, RTA_DATA(rta), gw, sizeof(gw)))
356                     return false;
357                 continue;
358             case RTA_OIF:
359                 if (maybeLogDuplicateAttribute(*dev, "RTA_OIF", msgname))
360                     continue;
361                 if (!if_indextoname(* (int *) RTA_DATA(rta), dev))
362                     return false;
363             default:
364                 continue;
365         }
366     }
367 
368    // If there's no RTA_DST attribute, then:
369    // - If the prefix length is zero, it's the default route.
370    // - If the prefix length is nonzero, there's something we don't understand.
371    //   Ignore the event.
372    if (!*dst && !prefixLength) {
373         if (family == AF_INET) {
374             strncpy(dst, "0.0.0.0", sizeof(dst));
375         } else if (family == AF_INET6) {
376             strncpy(dst, "::", sizeof(dst));
377         }
378     }
379 
380     // A useful route must have a destination and at least either a gateway or
381     // an interface.
382     if (!*dst || (!*gw && !*dev))
383         return false;
384 
385     // Fill in netlink event information.
386     mAction = (type == RTM_NEWROUTE) ? Action::kRouteUpdated :
387                                        Action::kRouteRemoved;
388     mSubsystem = strdup("net");
389     asprintf(&mParams[0], "ROUTE=%s/%d", dst, prefixLength);
390     asprintf(&mParams[1], "GATEWAY=%s", (*gw) ? gw : "");
391     asprintf(&mParams[2], "INTERFACE=%s", (*dev) ? dev : "");
392 
393     return true;
394 }
395 
396 /*
397  * Parse a RTM_NEWNDUSEROPT message.
398  */
parseNdUserOptMessage(const struct nlmsghdr * nh)399 bool NetlinkEvent::parseNdUserOptMessage(const struct nlmsghdr *nh) {
400     struct nduseroptmsg *msg = (struct nduseroptmsg *) NLMSG_DATA(nh);
401     if (!checkRtNetlinkLength(nh, sizeof(*msg)))
402         return false;
403 
404     // Check the length is valid.
405     int len = NLMSG_PAYLOAD(nh, sizeof(*msg));
406     if (msg->nduseropt_opts_len > len) {
407         SLOGE("RTM_NEWNDUSEROPT invalid length %d > %d\n",
408               msg->nduseropt_opts_len, len);
409         return false;
410     }
411     len = msg->nduseropt_opts_len;
412 
413     // Check address family and packet type.
414     if (msg->nduseropt_family != AF_INET6) {
415         SLOGE("RTM_NEWNDUSEROPT message for unknown family %d\n",
416               msg->nduseropt_family);
417         return false;
418     }
419 
420     if (msg->nduseropt_icmp_type != ND_ROUTER_ADVERT ||
421         msg->nduseropt_icmp_code != 0) {
422         SLOGE("RTM_NEWNDUSEROPT message for unknown ICMPv6 type/code %d/%d\n",
423               msg->nduseropt_icmp_type, msg->nduseropt_icmp_code);
424         return false;
425     }
426 
427     // Find the interface name.
428     char ifname[IFNAMSIZ];
429     if (!if_indextoname(msg->nduseropt_ifindex, ifname)) {
430         SLOGE("RTM_NEWNDUSEROPT on unknown ifindex %d\n",
431               msg->nduseropt_ifindex);
432         return false;
433     }
434 
435     // The kernel sends a separate netlink message for each ND option in the RA.
436     // So only parse the first ND option in the message.
437     struct nd_opt_hdr *opthdr = (struct nd_opt_hdr *) (msg + 1);
438 
439     // The length is in multiples of 8 octets.
440     uint16_t optlen = opthdr->nd_opt_len;
441     if (optlen * 8 > len) {
442         SLOGE("Invalid option length %d > %d for ND option %d\n",
443               optlen * 8, len, opthdr->nd_opt_type);
444         return false;
445     }
446 
447     if (opthdr->nd_opt_type == ND_OPT_RDNSS) {
448         // DNS Servers (RFC 6106).
449         // Each address takes up 2*8 octets, and the header takes up 8 octets.
450         // So for a valid option with one or more addresses, optlen must be
451         // odd and greater than 1.
452         if ((optlen < 3) || !(optlen & 0x1)) {
453             SLOGE("Invalid optlen %d for RDNSS option\n", optlen);
454             return false;
455         }
456         const int numaddrs = (optlen - 1) / 2;
457 
458         // Find the lifetime.
459         struct nd_opt_rdnss *rndss_opt = (struct nd_opt_rdnss *) opthdr;
460         const uint32_t lifetime = ntohl(rndss_opt->nd_opt_rdnss_lifetime);
461 
462         // Construct "SERVERS=<comma-separated string of DNS addresses>".
463         static const char kServerTag[] = "SERVERS=";
464         static const size_t kTagLength = strlen(kServerTag);
465         // Reserve sufficient space for an IPv6 link-local address: all but the
466         // last address are followed by ','; the last is followed by '\0'.
467         static const size_t kMaxSingleAddressLength =
468                 INET6_ADDRSTRLEN + strlen("%") + IFNAMSIZ + strlen(",");
469         const size_t bufsize = kTagLength + numaddrs * kMaxSingleAddressLength;
470         char *buf = (char *) malloc(bufsize);
471         if (!buf) {
472             SLOGE("RDNSS option: out of memory\n");
473             return false;
474         }
475         strcpy(buf, kServerTag);
476         size_t pos = kTagLength;
477 
478         struct in6_addr *addrs = (struct in6_addr *) (rndss_opt + 1);
479         for (int i = 0; i < numaddrs; i++) {
480             if (i > 0) {
481                 buf[pos++] = ',';
482             }
483             inet_ntop(AF_INET6, addrs + i, buf + pos, bufsize - pos);
484             pos += strlen(buf + pos);
485             if (IN6_IS_ADDR_LINKLOCAL(addrs + i)) {
486                 buf[pos++] = '%';
487                 pos += strlcpy(buf + pos, ifname, bufsize - pos);
488             }
489         }
490         buf[pos] = '\0';
491 
492         mAction = Action::kRdnss;
493         mSubsystem = strdup("net");
494         asprintf(&mParams[0], "INTERFACE=%s", ifname);
495         asprintf(&mParams[1], "LIFETIME=%u", lifetime);
496         mParams[2] = buf;
497     } else {
498         SLOGD("Unknown ND option type %d\n", opthdr->nd_opt_type);
499         return false;
500     }
501 
502     return true;
503 }
504 
505 /*
506  * Parse a binary message from a NETLINK_ROUTE netlink socket.
507  *
508  * Note that this function can only parse one message, because the message's
509  * content has to be stored in the class's member variables (mAction,
510  * mSubsystem, etc.). Invalid or unrecognized messages are skipped, but if
511  * there are multiple valid messages in the buffer, only the first one will be
512  * returned.
513  *
514  * TODO: consider only ever looking at the first message.
515  */
parseBinaryNetlinkMessage(char * buffer,int size)516 bool NetlinkEvent::parseBinaryNetlinkMessage(char *buffer, int size) {
517     struct nlmsghdr *nh;
518 
519     for (nh = (struct nlmsghdr *) buffer;
520          NLMSG_OK(nh, (unsigned) size) && (nh->nlmsg_type != NLMSG_DONE);
521          nh = NLMSG_NEXT(nh, size)) {
522 
523         if (!rtMessageName(nh->nlmsg_type)) {
524             SLOGD("Unexpected netlink message type %d\n", nh->nlmsg_type);
525             continue;
526         }
527 
528         if (nh->nlmsg_type == RTM_NEWLINK) {
529             if (parseIfInfoMessage(nh))
530                 return true;
531 
532         } else if (nh->nlmsg_type == LOCAL_QLOG_NL_EVENT) {
533             if (parseUlogPacketMessage(nh))
534                 return true;
535 
536         } else if (nh->nlmsg_type == RTM_NEWADDR ||
537                    nh->nlmsg_type == RTM_DELADDR) {
538             if (parseIfAddrMessage(nh))
539                 return true;
540 
541         } else if (nh->nlmsg_type == RTM_NEWROUTE ||
542                    nh->nlmsg_type == RTM_DELROUTE) {
543             if (parseRtMessage(nh))
544                 return true;
545 
546         } else if (nh->nlmsg_type == RTM_NEWNDUSEROPT) {
547             if (parseNdUserOptMessage(nh))
548                 return true;
549 
550         } else if (nh->nlmsg_type == LOCAL_NFLOG_PACKET) {
551             if (parseNfPacketMessage(nh))
552                 return true;
553 
554         }
555     }
556 
557     return false;
558 }
559 
560 /* If the string between 'str' and 'end' begins with 'prefixlen' characters
561  * from the 'prefix' array, then return 'str + prefixlen', otherwise return
562  * NULL.
563  */
564 static const char*
has_prefix(const char * str,const char * end,const char * prefix,size_t prefixlen)565 has_prefix(const char* str, const char* end, const char* prefix, size_t prefixlen)
566 {
567     if ((end-str) >= (ptrdiff_t)prefixlen && !memcmp(str, prefix, prefixlen))
568         return str + prefixlen;
569     else
570         return NULL;
571 }
572 
573 /* Same as strlen(x) for constant string literals ONLY */
574 #define CONST_STRLEN(x)  (sizeof(x)-1)
575 
576 /* Convenience macro to call has_prefix with a constant string literal  */
577 #define HAS_CONST_PREFIX(str,end,prefix)  has_prefix((str),(end),prefix,CONST_STRLEN(prefix))
578 
579 
580 /*
581  * Parse an ASCII-formatted message from a NETLINK_KOBJECT_UEVENT
582  * netlink socket.
583  */
parseAsciiNetlinkMessage(char * buffer,int size)584 bool NetlinkEvent::parseAsciiNetlinkMessage(char *buffer, int size) {
585     const char *s = buffer;
586     const char *end;
587     int param_idx = 0;
588     int first = 1;
589 
590     if (size == 0)
591         return false;
592 
593     /* Ensure the buffer is zero-terminated, the code below depends on this */
594     buffer[size-1] = '\0';
595 
596     end = s + size;
597     while (s < end) {
598         if (first) {
599             const char *p;
600             /* buffer is 0-terminated, no need to check p < end */
601             for (p = s; *p != '@'; p++) {
602                 if (!*p) { /* no '@', should not happen */
603                     return false;
604                 }
605             }
606             mPath = strdup(p+1);
607             first = 0;
608         } else {
609             const char* a;
610             if ((a = HAS_CONST_PREFIX(s, end, "ACTION=")) != NULL) {
611                 if (!strcmp(a, "add"))
612                     mAction = Action::kAdd;
613                 else if (!strcmp(a, "remove"))
614                     mAction = Action::kRemove;
615                 else if (!strcmp(a, "change"))
616                     mAction = Action::kChange;
617             } else if ((a = HAS_CONST_PREFIX(s, end, "SEQNUM=")) != NULL) {
618                 mSeq = atoi(a);
619             } else if ((a = HAS_CONST_PREFIX(s, end, "SUBSYSTEM=")) != NULL) {
620                 mSubsystem = strdup(a);
621             } else if (param_idx < NL_PARAMS_MAX) {
622                 mParams[param_idx++] = strdup(s);
623             }
624         }
625         s += strlen(s) + 1;
626     }
627     return true;
628 }
629 
decode(char * buffer,int size,int format)630 bool NetlinkEvent::decode(char *buffer, int size, int format) {
631     if (format == NetlinkListener::NETLINK_FORMAT_BINARY
632             || format == NetlinkListener::NETLINK_FORMAT_BINARY_UNICAST) {
633         return parseBinaryNetlinkMessage(buffer, size);
634     } else {
635         return parseAsciiNetlinkMessage(buffer, size);
636     }
637 }
638 
findParam(const char * paramName)639 const char *NetlinkEvent::findParam(const char *paramName) {
640     size_t len = strlen(paramName);
641     for (int i = 0; i < NL_PARAMS_MAX && mParams[i] != NULL; ++i) {
642         const char *ptr = mParams[i] + len;
643         if (!strncmp(mParams[i], paramName, len) && *ptr == '=')
644             return ++ptr;
645     }
646 
647     SLOGE("NetlinkEvent::FindParam(): Parameter '%s' not found", paramName);
648     return NULL;
649 }
650